Next time you seal your asphalt driveway please consider choosing an acrylic, latex or asphalt emulsion instead of a coal tar based sealant. Coal tar contains high levels of Polycyclic Aromatic Hydrocarbons (PAHs). According to the International Agency for Research on Cancer, PAH compounds have been proven to be carcinogenic, mutagenic, and teratogenic (causes birth defects) to humans.
Coal tar is a byproduct of the coking, liquification or gasification of coal. Coal tar pitch, the substance used in coal tar sealants, is the residue remaining after coal tar distillation. Coal tar is a waste product that has been turned into a commodity. After coal tar sealant dries it gradually abrades to a powder. This powder can be tracked into your household. Those most at risk of exposure are young children and pets since they spend their time on the household floor and both may sometimes play directly on the driveway. Exposure to PAHs, especially early in childhood, has been linked by health professionals to an increased risk of lung, skin, bladder, and respiratory cancers. This powder will also wash down storm drains where it will be released into local streams and impact wildlife. This residue has been shown to be lethal to fish and cause a wide spectrum of abnormalities to fish embryos. Because the coal tar abrades it needs to be reapplied every 2-5 years.
Some major retailers have stopped selling coal tar-based sealants, these include: Home Depot, Lowe’s, Ace, and United Hardware. Despite restrictions, coal tar sealers are still frequently used across the Chicago metro area.
The Illinois’ Coal Tar Sealant Disclosure Law goes into effect in 2023. This requires parental notification if sealers are proposed at schools as well as provisions for sealer used on State owned property.
In 2016 the American Medical Association (AMA) adopted a policy aimed at reducing or ending the use of coal tar-based sealcoats applied on pavement and playgrounds across the country. AMA board member Albert J. Osbahr, M.D. has officially stated the following:
“Whether they are sending their children to a playground or repairing a driveway, Americans are potentially being exposed to harmful carcinogens in coal-tar-based sealcoats, even if one’s exposure is limited, as sealcoats erode over time, PAHs leach into the water, soil and air, finding their way into sediment and eventually into aquatic wildlife. We must take action to either eliminate the use of PAH altogether or dramatically reduce its concentration in coal-tar sealcoats.”
However, it may not be enough to simply restrict coal tar use. In recent years other industrial waste products (such as a byproduct of the plastics industry “ethylene cracked residue” or ECR) containing high levels of PAHs have been marketed as asphalt sealants. Coal tar sealants on average contain 7% PAH, ECR sealants contain up to 3% PAH and asphalt-based sealants on average contain .005% PAH.
The best way homeowners can protect their family and pets is by choosing a PAH free driveway sealant (there are acrylic or latex based PAH free alternatives) or a low PAH level option such as asphalt-based sealant. If you are considering a new driveway, permeable pavers or concrete are the best options as they do not require these sealants.
For more information, please visit:
https://www.usgs.gov/mission-areas/water-resources/science/coal-tar-based-pavement-sealcoat-pahs-and-environmental